Plotters are used to produce precise and good quality graphics and drawings. they use an ink pen or inkjet, a single coloured or multicoloured pens. The pens are driven by a motor. Pen plotters are slow. Drawings can be prepared on paper vellum or mylar (polyester film). colour transparencies can also be prepared with the help of pen plotters. there are different types of pen plotters:
1. Drum plotters
A drum plotter contains a long cylinder and a pen cartridge. The drum rotates under the control of plotting instructions sent by the computer either in clockwise or anti-clockwise direction. the pen is mounted horizontally on the carriage and moves horizontally under the computer's control with the carriage left to right and right to left on the paper to produce a drawing. Pens with inks of different colours can be mounted on the carriage and multicoloured drawings can be produced.
2. Micro-grip Plotter:
This type of plotter do not use a drum. the paper or any other medium is held on both sides at the edges by pinch wheels which ensure back and forth movement of the paper.
3. Flatbed Plotter:
A flatbed plotter consists of a horizontal flat surface on which paper or any other medium is fixed. the pen is mounted on a carriage which can move along the horizontal and vertical axis.
These plotters are capable of producing large multicoloured drawings while closing inkjets in place of ink pens. the paper is placed on a drum and inkjets with different coloured inks are mounted on a carriage.